Stifling silos: The need for a more holistic approach to mixed migration in a warming world

The following essay was originally compiled for the Mixed Migration Review 2021 and has been reproduced here for wider access through this website’s readership.

The essay’s author Caroline Zickgraf is the deputy director of the University of Liège’s Hugo Observatory, which is exclusively dedicated to the study of environmental migration. In this capacity she is also the scientific coordinator of the HABITABLE project, which is discussed later in this essay.


Climate change and migration are defining geopolitical issues of the 21st century. They both challenge existing notions of national sovereignty, social justice, human rights, and moral responsibility in an increasingly globalised world. Despite their structural division into different policy silos, these are not separate issues at all. With global average temperatures on track to exceed the global target of two degrees specific warming levels established in the 2015 Paris Agreement, a major concern is what this will mean for geopolitical landscapes, including migration and displacement patterns.

Forced migration has long been touted as one of the key threats posed by a warming world. Many “futurologies”, especially those coming from European and North American perspectives, warn of an impending migration crisis if urgent climate action is not undertaken. With their emphasis on large-scale forced migration, rarely do these fear-based narratives acknowledge the spectrum of agency involved in population movements—both voluntary and involuntary—associated with climate change that is so characteristic of mixed migration. Migration is not always evidence of a failure to adapt to changing conditions. In some cases, studies show the opposite: migration is adaptation.

Even though current migratory responses and historical analogues provide valuable sources of information about what might happen in the years to come, environmental narratives that are exclusively focused on the future conditional fail to recognise that migration is already underway. The  volume,  character,  and  geographies of mixed migration are being  affected  by  the  slow and sudden  impacts  of  climate  change,  especially in vulnerable deltaic areas, small-island states, and sub-Saharan Africa. However, sea-level rise, increasing temperatures, climatic variability, and extreme events do not create a new type of migrant but rather transform the existing mobility landscape, necessitating the development of coalitions of actors and integrated, evidence-based strategies.

This essay focuses on the challenges of envisioning, and responding to, mixed migration in a warming world based on existing quantitative and qualitative empirical evidence.

Mixed drivers, mixed migration

Policymakers and the public alike have demonstrated a strong appetite to focus on numbers when it comes to the intersection of climate change and human migration. Although often misused and misrepresented, estimates help stakeholders grapple with the weight of the issue, and, subsequently, to plan for the future, including how and where to allocate resources and plan interventions. Despite being a notoriously difficult task, scientific methodologies have been advanced significantly in the past two decades. A group of experts gathered by the World Bank, for example, used gravitational modelling to produce a possible range of the number of internal climate migrants for three world regions in the first Groundswell Report in 2018. The Internal Displacement Monitoring Centre (IDMC) uses information about recorded and forecasted hazards to model the risk of future displacement and to estimate how many people will be forced to flee a given location each year, decade, or century. However, neither model accounts for mixed migration, diverse migration motivations, trajectories, or destinations. The World Bank focuses on internal climate migrants, the IDMC on disaster displacement. The same issue extends to contemporary estimates: we know that in 2020 more than 30 million new internal displacements occurred as a result of a sudden-onset disasters, but we have no figure that encompasses all forms of migration, including as a result of slow-onset events, voluntary movements, or international migration.

Indirect relationships

One reason that researchers struggle to grapple with mixed migration in the context of climate change is that the relationship between climate and migration is indirect; it is mediated by a number of intervening structural and individual factors, and this results in a range of non-linear migration patterns and outcomes. The assumed direct link between climate change and human mobility is not clear and future prognosis is ambiguous because the ways in which climate change and human mobility collide are complex, dynamic, and rooted in local landscapes, including policy decisions. Climate change acts as a threat—or rather a vulnerability—multiplier, exposing and exacerbating pre-existing vulnerabilities of those affected, rather than creating them outright. This, too, holds true for the ways in which climate change affects mixed migration. Changing environmental conditions interact with other drivers of migration, be they social, political, economic, environmental, or demographic. In turn, they can transform mixed migration dynamics by making certain destinations or routes less attractive, for example, or by increasing the intensity and frequency of disasters and associated loss and damage.

The impacts of climate change do not result in new or distinct “climate migrants” or “climate refugees.” All migration is multi-causal, and climatic factors are not necessarily the most prominent motivation for migrants, internally displaced people, asylum seekers or refugees moving within fragile environmental contexts. Studies in various regions of the world repeatedly demonstrate that one of the most significant pathways between climate change and human mobility is the indirect livelihood pathway, especially in the face of more gradual environmental changes. People who are amongst the most vulnerable to the impacts of climate change are those whose livelihoods depend on their physical environment, as are countries whose economies depend on agriculture. This vulnerability, in turn, can make people likely candidates for migration when changing maritime currents, erratic rainfall, or soil salinisation, for example, render livelihoods dependent on natural resources unsustainable in situ. Frequently, in surveys and qualitative interviews, people moving in response to gradual climate impacts describe their motivations as largely economic (seeking more stable income, job opportunities, etc.). In these circumstances, the scientific consensus is that economic migration is environmental migration.

Conflict complexities

The obfuscation of environmental drivers is not unique to livelihood pathways or more “voluntary” forms of migration. Conflict and environmental change can amplify each other to drive mass displacement, such as when armed forces destroy or deplete local resources (which may, in turn, fuel local tensions) or when a population ravaged by war is then devastated by a natural hazard. Conflict and climate change can also act in opposition to one another, forcing people affected to evaluate various risks and respond to the gravest threats through movement or stasis. Women who traditionally migrated in response to drought in wartime Mozambique were prevented from doing so because of surrounding conflict, becoming what one scholar referred to as “displaced in situ”. Burkina Faso has witnessed one of the most rapidly evolving humanitarian crises in the world, with more than 1.2 million displaced since 2019. According to local and international organisations working on climate, conflict, and migration, Burkinabés’ primary and most pressing concern was physical security and escaping conflict. Though the country faces severe environmental degradation, environmental conditions do not play a big role determining their subsequent migration patterns.

Quantitative research into mixed migration in Africa demonstrates that people themselves seldom identify as environmental migrants or climate refugees. In a 2021 survey of more than 2,000 refugees and migrants in West and North Africa, few respondents listed “natural disaster or environmental factors” as playing a role in their departure (two percent in West Africa and six percent in Central Africa), and none of these respondents cited this as their sole reason for leaving. This does not mean, however, that the environment played no part in their migration. When asked directly whether environmental issues were a factor in their decision to leave their country, 48 percent of the survey’s overall respondents indicated that environmental factors or natural disasters contributed to their decision to migrate (47 percent in West Africa and 53 percent in Central Africa), which was mainly related to economic drivers. This supports previous studies showing that when explicit questions about the possible linkages between environment and migration are avoided, environmental stress was not mentioned as a key driver of migration.

Mixed dynamics

Accepting that climate is only one element in a mix of migration drivers helps to explain where  people  go and where they may move to in the future, and thus to identify critical intervention points. People on the move in a warming world join and travel within the same “migration circuits” as other migrants or displaced people. Rural-to-urban migration is the most frequently observed trajectory (although it is not the only one) when rural agricultural livelihoods become untenable and as people move to cities seeking better opportunities. In these circumstances, one cannot isolate climate migration patterns from broader rural-to-urban migration trends.

Urban risks

Urbanisation is likely to continue in the future given the concentration of opportunities and capital in cities even when urban spaces are environmentally fragile. Cities are the main destinations of migration (regardless of motivation), but they are also exposed to the impacts of extreme environmental events. Migration into cities increases risk, especially when migrants or refugees find themselves in precarious living conditions and socially or economically marginalised. People moving into informal settlements built on flood plains or hillsides, without access to infrastructure or social services, are at risk of secondary displacement when floods, landslides, or other urban disasters strike. The same people may be economic migrants at one stage, and disaster displaced persons at another. Likewise, they may begin as conflict refugees and then be displaced by climate impacts. Cities can also be primary origin points of displacement and outward migration in developing countries and developed countries alike, the former demonstrated famously by the case of Hurricane Katrina in New Orleans and recently during the July 2021 floods in Germany and Belgium. Cities are also origin points of livelihood migration, as in the case of coastal fisheries in urban and peri-urban areas. Therefore, effectively addressing climate and migration in cities requires preparing for in-migration, transit migration, and out-migration, decreasing urban displacement risk, and generally incorporating planned migration in sustainable development strategies.

Internal migration is the most frequently documented dynamic associated with climate change. International mixed migration flows can also include those who were affected by climate change in their communities of origin or at another point in their migration journey. Studies on international migration, which are less common than those detailing internal migration, are somewhat ambiguous in their findings. One study on asylum applications in the European Union from 103 source countries found a statistically significant relationship between fluctuations in asylum applications and weather anomalies over the period 2000 to 2014. Holding everything else constant, its authors predict a 28 percent increase in annual asylum applications under representative concentration pathway (RCP) scenario 4.5 and by 188 percent under RCP 8.5. However, other studies challenge the idea that the European Union should expect more migration. A 2021 study found no evidence that drought in a sending country increased irregular migration flows to the European Union.  Rather, drought seems to exert a negative, albeit moderate, impact on the size of migration flows, especially those from countries dependent on agriculture (although this is not a conclusive finding). In different contexts, this may be explained by the negative impact of drought on migration resources, where the household diverts all resources towards basic survival and functioning (e.g. food, water, shelter) or because households become accustomed to cyclical drought and do not perceive it as a “shock” event.

Not always a last resort

Generally, public and media narratives on the climate- migration nexus emphasise forced migration at the expense of more voluntary forms, demonstrated by the common usage of “climate refugees” despite the lack of legal standing of the term. That is because migration, even when not spontaneous, is seen as an indication of a failure to adapt to changing environmental conditions. Statistically, the figures used to highlight the significance of environmental migration are disaster displacement statistics, giving the impression that environmental migration is first and foremost about sudden-onset disasters forcing people to flee. Some individuals or households exhaust all other options before engaging in migration, most clearly in response to rapidly occurring disasters, but also in response to impacts of creeping environmental changes. Migration and even displacement in these cases is a coping strategy, a short-term survival mechanism.

Migration as adaptation

However, empirical evidence shows that migration is not always a last resort. Some people depart entirely voluntarily, some are forced to flee, but most people fall somewhere in between these two ends of the agency spectrum. Not all who move do so because they have no other choice. Especially for those living in “migration cultures”, where migration is a normal part of life, migration is one of many adaptation options. Households can and often do prefer it to negative coping strategies such as selling off assets or decreasing food intake. They may send one or more members elsewhere to diversify income and take the pressure of off local livelihoods. In coastal areas of Senegal, fishers migrate to Mauritania in response to overfishing and maritime climate impacts, returning with income gained abroad and then financing self-relocation away from coastal erosion. For pastoralist populations, such as those in the Sahel, migration is a traditional strategy to navigate harsh or changing environmental conditions. In fact, for such communities it is immobility or sedentarism that represents a disruption to daily life.

Mixed immobility

Standing in contrast to those who migrate—by choice or by force—are those who do not leave at all. Research on immobile populations rebuts the purported mass migration threat frequently associated with future climate change and challenges the assumption that as the magnitude of climate impacts increase, so too will migration. Externally, it may seem logical that the more unstable a local climate is, the more likely people are to move. However, an important emerging line of research demonstrates that, in some cases, the opposite may be true. That is to say, people may be less able to migrate as environmental conditions adversely impact their assets, leaving them without the resources necessary to move out of harm’s way. Consequently, these people may be among the most vulnerable to an array of climate impacts, including those on health and wellbeing, and face a higher risk of mortality and displacement.

But all those who are immobile are not necessarily “trapped”. People who stay in fragile areas do so for a number of reasons, including place attachment and land ownership. Despite experiencing adverse impacts of climate change on health and livelihoods, indigenous people of the Pacific in places like Fiji are increasingly expressing a preference to stay on their lands for cultural and spiritual reasons. Therefore, the spectrum of human mobility associated with climate change includes not only mixed migration but also mixed immobility. A nuanced understanding of the nexus between climate change and mixed migration needs to consider the full spectrum of mobility and immobility drivers and outcomes associated with climate change. Mobility can be variously a sign of positive coping or adaptation and a negative measure of last resort. Similarly, immobility can be both a sign of positive adaptive capacity to stay in place and one of desperation and extreme  vulnerability.  Each  of these outcomes offer insight into  how  communities and households are affected and how they adapt, and suggest different programmatic and policy responses.

Perceptions of habitability

The notion of habitability is set to be at the core of future thinking on migration and climate change. Mass migration is expected to occur when places reach a climate tipping point, becoming uninhabitable in a physical sense, for example when temperatures in the Middle East exceed the limits of the human body. Yet, as explained above, migration is not determined by environmental concerns alone. Thus, models of future migration and displacement often consider a number of socio-economic and development pathways alongside climate parameters.

Ground-level views

Most available models, however, are based on objective determinations of environmental changes, using, for example, data on rainfall or temperature variations. But populations’ decisions to evacuate, flee, or migrate are made based on their own perceptions of climate impacts and other environmental changes, their own vulnerability, and their aspirations and capabilities to move or to stay. People’s choices of whether, when, and where to go are based on what they perceive to be happening to their surroundings, which does not always align with externally observed climate data.

Using the household African Monsoon Multidisciplinary Analysis survey in Burkina Faso, one study found that that respondents perceived increasing temperatures and worsening rainfall conditions over the period 1988–2007, which was inconsistent with the trends observed in rainfall data. In some cases, opinions about rainfall conditions varied within the same populations: in one site, 64.5 percent of respondents perceived a decrease in the intensity of rainfall events, while 28.9 percent reported an increase. Likewise, opinions about whether migration is a positive or negative consequence of climate variability were divided. Other qualitative studies have also showed that the perceptions of climate change can influence migration decisions.

Work on perceptions of migrants, displaced people, and non-migrants may help to produce knowledge grounded in local experiences and perspectives. Considering the perceptions of populations also entails collecting data on their migration aspirations and capabilities—whether, for example, they see migration as a viable adaptive strategy or a last resort. For this reason, new scientific research sets out to capture how migrants and non-migrants alike perceive changes in their physical environments, the drivers of their (actual or potential) migration, and the perceived outcomes in conjunction with climate data. The HABITABLE project, launched in 2020, is deploying a series of methods to capture how people themselves understand the links between migration and climate change, including fuzzy cognitive mapping, in sub-Saharan Africa and Southeast Asia, in order better understand current movements and to inform future modelling and qualitative scenarios. The project conceptualises habitability as a social and physical construct that results from the perceptions of the affected populations about all aspects of their lives, including economic, political, social, economic, and demographic considerations. A “social tipping point” may be reached well before a “climate tipping point”, but adaptive migration may also make places more inhabitable. In the former case, the negative economic consequences of climate change may overwhelm socio-ecological systems before they become physically uninhabitable. In the latter, out-migration may generate social and financial remittances that facilitate technological adaptation solutions in communities of origin and/or decrease population pressure on dwindling natural resources.

The current policy silo approach: developing shared tools to address mixed migration

Responding to and preparing for mixed migration (and immobility) requires the participation of a number of actors in the traditionally separate domains of climate change, development, and migration, but also those in a number of other fields: disaster risk reduction, humanitarian action, development, and urban planning. Currently, governmental structures bound by institutional and operational mandates are ill-equipped to treat such complex, and cross-cutting issues. This results from a silo approach at the international, national, and local scales.

Policy and organisational silos hinder the development of comprehensive durable solutions for mixed migration in a warming world. Representatives of ministries responsible for migration are rarely seen at the annual United Nations Framework Convention on Climate Change (UNFCCC) climate negotiations. The same can be said for environmental representation in the Global Compact for Migration (GCM) discussions. Each realm is then left without the range of expertise necessary to make informed, cohesive decisions. Coordination across policy processes then falls to international organisations and civil society members tracking parallel negotiations and developments, such as the Platform on Disaster Displacement or the International Organization for Migration.

Questions of priority

Mixed migration related to climate change has predominantly been taken up in the climate policy arena rather than in migration governance. Frequently (though not always), these discussions centre on the risks of forced migration posed by unabated greenhouse gas emissions, thus focusing on mitigation rather than pre-emptive migration and relocation as a policy solution. In UNFCCC processes, averting, minimising, and addressing displacement remains the priority, as demonstrated by the establishment of the Task Force on Displacement under the Warsaw International Mechanism for Loss and Damage  Executive  Committee.  However, migration as adaptation was recognised in the 2010 Cancun Framework and, as of 2021, technical guides are being developed that help parties address a range of human mobility outcomes. These are promising developments that shift away from (exclusively) “doom and gloom” migration discourses and towards more nuanced policy approaches on mixed migration.

States and stakeholders have afforded relatively less attention to issues of climate change and environmental degradation in international migration governance, perhaps in part because of the thorny  legal  issues they raise. Successive drafts of the Global Compact on Refugees watered down wording on disasters after concern from states about broadening the scope of refugee status. Eventually, they merely  recognised that “climate, environmental degradation and natural disasters increasingly interact with the drivers  of refugee movement.” The GCM engaged more strongly with environmental issues, acknowledging  the  role of environmental degradation, disasters, and climate impacts as “root causes” of migration that should be addressed by governments. The GCM recognises that its success rests on a number of global instruments beyond migration governance: the UNFCCC and the Paris Climate Agreement, the United Nations Convention to Combat Desertification, the 2030 Agenda for Sustainable Development, and the Sendai Framework for Disaster Risk Reduction. This opens up opportunities for future policy coherence across migration, climate change, sustainable development and disaster risk reduction.  However, with environmental concerns only now emerging within migration governance, implementation will rely on political will, adequate funding, and the establishment of coalitions interested in transformative governance.


Without improved coordination and communication across silos and between international, national, and local scales, actors in one policy domain have at times acted against the interests of another. The issue of climate and migration gathers a set of governmental and civil society actors that do not always agree on policy objectives and the strategies to achieve them. Environmental activists often play into fears of mass migration from the Global South to the Global North to inspire climate action in the form of mitigation—the cutting of greenhouse gas emissions to address the “climate emergency.” These discourses posit migration as both a humanitarian and security threat and hinge on aquatic language—such as “tide”, “waves”, “floods” and “surges”, etc.—implying that migration linked to climate change is a negative outcome for migrants and destinations alike. This leaves little room for migration to be considered as a policy solution rather than a policy problem. In 2007, one leading international aid agency warned that without urgent action, an “emerging migration crisis will spiral out of control.” It predicted some one billion people would be forced to flee by 2050.

Since early interest in climate migration, in fact, narratives on future displacement have claimed millions or even billions of climate refugees will be on the move by 2050. Although quantitative methodologies have advanced, we still see such numbers being put forth without scientific rigour. In 2020, one think tank claimed that some 1.2 billion people would migrate because of climate change, a large portion of which would go to Europe, bringing with them political instability. This claim was then picked up by the international press and widely circulated despite being severely criticised by experts for the author’s reliance on fear rather than facts. The danger here is that in the quest to achieve one kind of climate action (mitigation) migration is weaponised. This can have impacts on migration policies that reduce international protections and restrict legal migration channels.

A better way forward

One possible pathway towards transformative approaches to climate and migration, in science and governance, that is inclusive of mixed migration and facilitative of cross-sectoral coherence is the co-production of a shared set of tools based on evidence. The development of a common set of migration scenarios with qualitative and quantitative components, rather than a single (numeric) vision of the future, may help to prepare for several possible worlds in a way that considers the multi-faceted causality of migration, the full spectrum of mobility and immobility, the diverse patterns that occur, and the positive and negative outcomes that result. Such an approach would also facilitate science- policy collaboration. Research helps inform evidence- based policy responses, but scientists underline that policy is also part of a feedback loop: an important factor influencing how climate change affects diverse patterns and outcomes of migration. Therefore, instead of “giving” scenarios to inform policy, this approach co-produces them with the range of interested and influential policymakers and other stakeholders, integrating multiple policy perspectives for more cohesive and collaborative decision-making.


The impact of climate change is unfolding against a backdrop of globalisation and urbanisation, in which mobility is already a significant feature of many societies. Climate change alters the existing mobility landscape. It is just one of many elements shaping human settlements. Thus, envisioning climate mobility in a warmer world requires thinking about the future of all mixed migration.

Boxing “climate migrants” or “climate refugees” hinders cohesive policy strategies and alliances across a number of relevant domains: climate change, disaster risk reduction, humanitarian response, sustainable development, and migration governance. The silo approach, which has thus far dominated policy responses at all governance scales, has proven ineffective and even counterproductive to addressing mixed migration in a warming world. The dysfunctionality of treating migration and climate change as separate policy-making silos or as a future hypothetical will become increasingly obvious as the impacts of climate change intensify and become more important drivers of human mobility.

A common, co-produced set of scenarios of future habitability may not banish silos, but it may help create shared understandings and tools for cross-sectoral decision-making. The development of such scenarios will also benefit from the inclusion of local populations. In general, voices of affected populations, whether they are immobile or mobile, are rarely elevated in public discourses or international policy discussions on climate change such as the UNFCCC’s annual Conference of the Parties (COP). This presents an obstacle for policy strategies tailored to the needs  and  desires  of  those  directly and indirectly affected by climate change, including migrants and displaced persons but also those who are immobile. Bringing together the diverse perspectives of these stakeholders can build more accurate pictures of what mobility may look like in a climate changed world, inclusive of a spectrum of migration rather than distinguishing forced from voluntary migration, or internal from international migration.